Biodiversity and Conservation
Core concepts
Know the levels of biodiversity (genetic, species, ecosystem) and the measures of species diversity (species richness, evenness, Shannon and Simpson indices). Understand hotspots, endemism, and the distribution of biodiversity (latitudinal gradient). Study threats: habitat loss and fragmentation, overexploitation, invasive species, pollution, climate change, and disease. Learn conservation strategies - in situ (protected areas, biosphere reserves with core, buffer, and transition zones) and ex situ (zoos, seed banks, cryopreservation), plus the IUCN Red List categories (Least Concern through Extinct). Understand the Convention on Biological Diversity, CITES, and the Nagoya Protocol. Know the concept of minimum viable population and the role of corridors.
Common traps
Do not confuse species richness with diversity; a community can be rich but uneven. Critically Endangered is more severe than Endangered, and Extinct in the Wild differs from Extinct. Hotspots are defined by endemism and habitat loss, not simply by total species count. In situ conservation keeps organisms in their habitat; ex situ removes them.
Worked example
Rule of thumb: to compare two communities, compute richness first, then evenness. A community with 10 species where one dominates is less diverse than a community of 8 evenly distributed species. Simpson's index emphasizes dominance, so a higher value indicates lower diversity in that formulation - always check the version used.